The present invention relates generally to machine vision, and more particularly to machine vision systems for forming a digital representation of a low information content scene, e.g., a scene that is sparsely illuminated by an illumination plane.
A well-known method for acquiring 3D range images includes steps of: providing a light source with line generating optics to illuminate a single plane of a scene, positioning a digital camera to view the light plane such that objects illuminated by the light source appear in the optical image formed by the camera lens, capturing a digital image of the scene, processing the digital image to extract the image coordinates of points in the scene illuminated by the light source, and processing the image coordinates according to the triangulation geometry of the optical system to form a set of physical coordinates suitable for measurement of objects in the scene.
A major limitation associated with such a conventional machine vision process is that a 2-dimensional intensity image of substantial size must be captured by the digital camera for each and every line of physical coordinates formed by the system. This can make the time to capture the 3D image of a scene as much as 100 times longer than the time required to acquire an intensity image of the same size scene, thereby rendering laser-line based 3D image formation methods too slow for many industrial machine-vision applications.